1. Field of the Invention
The present invention relates to standing seam roof assemblies, and more particularly but not by way of limitation, to improvements in components for a standing seam roof assembly and methods of installing same.
2. Brief Statement of the Prior Art
Specific problem areas in this field include the difficulty of designing a clip for standing seam roof panels that will resist uplift forces imposed on the clip while allowing the expansion and contraction movement between roof panels and their building supporting structurals. The clip tab should remain at the same position on the male side lap portion of the standing seam panel so that the sealant which is installed to provide a water seal between the top of the male apex of the male side lap portion and the sealant contained in the retaining cavity of the female side lap portion is not dislodged by differential movement of the clip tab and the male side lap portion. One approach to this is taught by Simpson and Holman in U.S. Pat. No. 4,497,151 wherein the clip tab tightly grips the male side lap portion by means of barbs that embed into the metal and prevent differential movement of the tab and the male side lap portion.
Another problem area involves the installation of the first run of panels on a standing seam roof system in that this must be accomplished so that the first panel is substantially true with the underlying secondary support structurals of the building. The reason for this is that the standing seam roof panels seam together continuously along their sides and there is no provision to overlap the panels more at one end of the panels than the other. The panels are relatively narrow so there is little opportunity to flex the panel by bowing or otherwise deforming the panel shape to overcome the angular track of a roof that is started out of alignment. Also contributing to the difficulty of correcting misalignment is the fact that the panel ends are usually factory punched and notched for attachment to each other at the ends and at the termination of the panels along the eave and the ridge. Thus, staggering of the panels to keep the ends in proper alignment can only be done to accommodate a very small amount of misalignment.
Most roof structurals are not square and true at the roof level even if they are at the ground level. This means that the starting edge of the first panel run will in many cases have to be established by measuring the structurals and establishing a start line that is independent of the skew of the structurals at the starting edge. This line is usually marked with a transit or chalk line along the top of the structural steel close to the end of the roof structurals.
The alignment problem is further complicated by the fact that the usual procedure is to install the underlying building insulation prior to installing the panels. The most common type of insulation in use is glass fiber blanket insulation with a vinyl vapor retardant on one side. The insulation is installed with the vapor retardant down and the glass fiber exposed from the top. The glass fiber in effect hides the structural system as far as observing the exact location of marks on the structurals is concerned. The spungy nature of the glass fiber blanket makes it difficult to precisely locate a clip, or angle member, such that the roof edge is in good alignment with the structural system. The glass fiber insulation also interferes with string lines to indicate the start location of the first panel run.
Another complicating design factor in developing a positive method of establishing the start location of the first panel run is the fact that the start attaching method must allow the roof panel to move longitudinally, independent of the structural system, for thermal expansion. Panel clips cannot be used as starters for most panel systems because most standing seam roof panels are installed with the male side lap portion as the leading edge; the panel clips are designed to attach to the male lip before the female side lap portion is seamed to the male side lap portion.
The termination rake detail for metal roof panels, where the roof panels are designed to expand and contract independently of their supporting structurals, has largely been left to the field erection crew. An exception is where the panel module is precisely controlled other than through the use of prepunched holes in the structural system. Another approach is the use of erection guides that require the erector to hold the panel within precise module.
Even when the erector is trying to hold the panel on module, it is generally not possible to guarantee the exact location of the male side lap portion of the roof panels when the end of the roof run is reached. For example, on a building that is 200 feet long: if the edge of a 26 gage panel--that is 3 inches higher than the panel flat and held in place by a clip fastened on top of a compressible blanket insulation--is allowed to be 1/32 inch too wide (1/32 inch increments not shown on construction tapes) then the cumulative growth of the panel edge over the length of the building would be more than 6 inches. The erector would usually discover this problem about 3 or 4 panels from the end of the panel run.
There are various methods for sealing the end of a panel slope to provide for expansion and contraction, but very few such methods will work if the panel is not on a precise module. The few that recognize this problem attempt to solve it by requiring extensive field bending or the use of a special width panel that may or may not be required to terminate the roof slope. These prior art solutions have obvious drawbacks in that the erector cannot wait to finish the roof while a few specially fabricated parts arrive without incurring additional costs and delays.
Another problem with most terminations of panel runs is the inability of the termination method to accommodate an out of square condition that inevitably occurs. This condition further complicates the design criteria which must accommodate the thermal expansion and contraction of the roof panels.
The installation of water resistant roof panels finds more difficulties at the eave rake detail of the roof system, especially for low sloped roof systems. Water running off the eave will run back under the roof panels for a distance of about 3 inches or more on a 1/4 inch to 12 inches sloped roof. An eave flashing is used along the intersection of the roof panels and the wall members where a gutter is not desired either for appearance or because of severe icing conditions. This eave flashing provides two primary functions: it hides the intersection of the roof and the wall with an attractive finishing detail; and it can seal the edge of the roof from water entry if properly designed and installed.
The usual method of designing the flashing is to have the upper edge of the flashing rest between the roof panel and the eave structural member. This method is prone to allow water to backup behind the panel and the flashing because there is no known way to positively seal the end of two roof panels in the field so they will never leak. When water does leak between the flashing it must have some way to exit other than into the building. Some prior art flashings attempt to solve this problem but they do not cover the fastener used to attach the flashing to the roof panel or they ignore the necessity of holding the flashing in place until the fastener is installed through the roof.
One other problem to be dealt with in the present disclosure is that of providing water tight openings in the roof panels for utility assemblies such as skylights. In usual practice, panel installation must be periodically held up while the utility openings are framed, often by special crews while the paneling crew stands by. Even then such utility assemblies often are not water tight or quickly become such as they are usually mounted in a stationary position while the surrounding panel members flex and move relative thereto; thus, special flashings and sealants must be constantly renewed, resulting in costly maintenance upkeep, not to mention unsightly roofing details.